1
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Huang YY, Yang J, Liu YB. Planning issues on linac-based stereotactic radiotherapy. World J Clin Cases 2022; 10:12822-12836. [PMID: 36568990 PMCID: PMC9782937 DOI: 10.12998/wjcc.v10.i35.12822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/20/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022] Open
Abstract
This work aims to summarize and evaluate the current planning progress based on the linear accelerator in stereotactic radiotherapy (SRT). The specific techniques include 3-dimensional conformal radiotherapy, dynamic conformal arc therapy, intensity-modulated radiotherapy, and volumetric-modulated arc therapy (VMAT). They are all designed to deliver higher doses to the target volume while reducing damage to normal tissues; among them, VMAT shows better prospects for application. This paper reviews and summarizes several issues on the planning of SRT to provide a reference for clinical application.
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Affiliation(s)
- Yang-Yang Huang
- School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, Jiangxi Province, China
- Department of Radiotherapy, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou 450014, Henan Province, China
| | - Jun Yang
- Department of Radiotherapy, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, Henan Province, China
| | - Yi-Bao Liu
- School of Nuclear Science and Engineering, East China University of Technology, Nanchang 330013, Jiangxi Province, China
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2
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Sohrabi M, Hakimi A. Spectrometry of leakage photoneutrons of 18 MV medical accelerator head by Sohrabi passive multi-directional spherical neutron spectrometry system. Phys Med 2022; 99:120-129. [DOI: 10.1016/j.ejmp.2022.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 04/24/2022] [Accepted: 04/27/2022] [Indexed: 10/18/2022] Open
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3
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Moghaddasi L, Colyer C. Evaluation of the effectiveness of steel for shielding photoneutrons produced in medical linear accelerators: A Monte Carlo particle transport study. Phys Med 2022; 98:53-62. [DOI: 10.1016/j.ejmp.2022.04.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/13/2022] [Accepted: 04/22/2022] [Indexed: 10/18/2022] Open
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4
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Measurement of neutron equivalent dose in the thyroid, chiasma, and lens for patients undergoing pelvic radiotherapy: A phantom study. Appl Radiat Isot 2022; 184:110188. [DOI: 10.1016/j.apradiso.2022.110188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/18/2022] [Accepted: 03/04/2022] [Indexed: 11/20/2022]
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5
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Sohrabi M, Torkamani ME. Breakthrough whole body energy-specific and tissue-specific photoneutron dosimetry by novel miniature neutron dosimeter/spectrometer. Sci Rep 2021; 11:20552. [PMID: 34654858 PMCID: PMC8519960 DOI: 10.1038/s41598-021-99612-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 09/28/2021] [Indexed: 11/09/2022] Open
Abstract
Breakthrough whole body energy-specific photoneutron (PN) dosimetry was made in/out-of-field in polyethylene phantom organ surface/depths remote from isocenter of 10 × 10 cm2 field prostate cancer therapy in 18 MV X-rays Varian Clinac 2100C medical linear accelerator for PN tissue-specific second primary cancer (PN-SPC) risk estimation. A novel miniature neutron dosimeter/spectrometer with polycarbonate/10B/cadmium inserts was invented and applied. Each dosimeter determines seven tissue-specific dose equivalent (mSv)/Gy X-ray dose at each measurement point providing seven major energy-specific responses for beam thermal, albedo thermal, total thermal, total epithermal, total fast, sum of totals (thermal + epithermal) and sum of totals (thermal + epithermal + fast) PNs dose equivalents. The neutron dosimeter is simple, efficient, and unique with high spatial resolution and provides matrix of energy-specific PN dose equivalent (mSv)/Gy X-ray dose on surface and organ depths for tissue-specific PN-SPC risk estimation. The dosimeter also performs like a "miniature neutron spectrometer" and is unique for other applications in health physics in particular individual neutron dosimetry, medical physics, space flights, science and technology.
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Affiliation(s)
- Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran.
| | - Morteza Ebrahimzadeh Torkamani
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran
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6
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Cheraghian M, Pourfallah T, Sabouri-Dodaran AA, Gholami M. Calculation of Photoneutron Contamination of Varian Linac in ICRU Soft-Tissue Phantom Using MCNPX Code. J Med Phys 2021; 46:116-124. [PMID: 34566292 PMCID: PMC8415253 DOI: 10.4103/jmp.jmp_40_21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 11/04/2022] Open
Abstract
Purpose The aim of this research was to calculate the fluence, dose equivalent (DE), and kerma of thermal, epithermal and fast photoneutrons separately, within ICRU soft-tissue-equivalent phantom in the radiotherapy treatment room, using MCNPX Monte Carlo code. Materials and Methods For this purpose, 18 MV Varian Linac 2100 C/D machine was simulated and desired quantities were calculated on the central axis and transverse directions at different depths. Results Maximum fluence, DE and kerma of total photoneutrons on central axis of the phantom were 43.8 n.cm-2.Gy-1, 0.26, and 3.62 mGy.Gy-1, at depths 2, 0.1, 0.1 cm, respectively. At any depth, average of fluence, DE and kerma in the outer area of the field were less than the inner area and in general were about 72%, 52%, and 45%, respectively. Conclusion According to this research, within the phantom; variation of fluence, DE and kerma in transverse direction were mild, and along the central axis at shallow area were sharp. DE of fast photoneutrons at shallow and deep areas were one order of magnitude greater than thermal photoneutrons.
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Affiliation(s)
| | - Tayyeb Pourfallah
- Department of Biochemistry, Biophysics and Genetics, Medical College, Mazandaran University of Medical Sciences, Sari, Iran.,Department of Medical Physics, Mazandaran University of Medical Sciences, Sari, Iran
| | | | - Mehrdad Gholami
- Department of Medical Physics, School of Allied Medical Sciences, Lorestan University of Medical Sciences, Khorramabad, Iran
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7
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Kakino R, Nakamura M, Hu N, Iramina H, Tanaka H, Sakurai Y, Mizowaki T. Photoneutron-induced damage reduction for cardiac implantable electronic devices using neutron-shielding sheets in high-energy X-ray radiotherapy: A phantom study. Phys Med 2021; 89:151-159. [PMID: 34371340 DOI: 10.1016/j.ejmp.2021.07.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 07/06/2021] [Accepted: 07/28/2021] [Indexed: 12/24/2022] Open
Abstract
PURPOSE To evaluate damage reduction in cardiac implantable electronic devices (CIEDs) caused by photoneutrons in high-energy X-ray radiotherapy using a neutron-shielding sheet (NSS). METHODS The NSS consists of a bolus with a thickness of 1 or 2 cm (Bls1 or Bls2) as a moderator and several absorbers (20%, 50%, or 80% B4C silicone sheet [B4C20, B4C50, or B4C80] or a 40% LiF silicone sheet [LiF40]). First, a linear accelerator (LINAC) with a water-equivalent phantom was modeled in the simulation and measured experimentally. Several NSSs were placed on the phantom, a Eu:LiCaAlF6 scintillator was placed between the phantom and the NSS, and X-rays were irradiated. The relative counts (Cr = counts when placing the NSS or Bls2) were compared between the experiment and simulation. Second, CIED damage was evaluated in the simulation. The relative damage (Dr = damage when placing or not placing the NSS) was compared among all the NSSs. In addition, the γ-ray and leaking X-ray dose from B4C was measured using a dosimetric film. After determining the optimal NSS combination, Dr value analysis was performed by changing the length of one side and the thickness. RESULTS The Cr values of the simulation and experiment agreed within a 30% percentage difference, except for Bare or LiF40-only. The Dr value was reduced by 43% when Bls2 + B4C80 was applied. The photon dose was less than 5 cGy/1500 MU. The Dr values were smaller for the smaller lengths of one side of B4C80 and decreased as the M-layer thickness increased. CONCLUSIONS The CIED damage induced by photoneutrons generated by a LINAC was effectively reduced by applying the optimal NSS.
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Affiliation(s)
- Ryo Kakino
- Division of Medical Physics, Department of Information Technology and Medical Engineering, Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan
| | - Mitsuhiro Nakamura
- Division of Medical Physics, Department of Information Technology and Medical Engineering, Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
| | - Naonori Hu
- Kansai BNCT Medical Center, Osaka Medical College, 2-7 Daigaku-Machi, Takatsuki, Osaka 569-8686, Japan; Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2 Asashiro-nishi Kumatori-cho, Osaka 590-0494, Japan
| | - Hiraku Iramina
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
| | - Hiroki Tanaka
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2 Asashiro-nishi Kumatori-cho, Osaka 590-0494, Japan
| | - Yoshinori Sakurai
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, 2 Asashiro-nishi Kumatori-cho, Osaka 590-0494, Japan
| | - Takashi Mizowaki
- Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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8
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Sohrabi M, Hakimi A. Photoneutron spectrometry by novel multi-directional spherical neutron spectrometry system. Sci Rep 2021; 11:3251. [PMID: 33547354 PMCID: PMC7864933 DOI: 10.1038/s41598-021-81529-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 01/07/2021] [Indexed: 01/30/2023] Open
Abstract
Neutron spectrometry in science and technology applications in general and accurate exotic photoneutron (PN) dosimetry of cancer patients undergoing high-dose high-energy X-rays therapy in medical accelerators in particular is of vital need. In this study, a novel passive multi-directional multi-detector neutron spectrometry system was developed and home-made using 6 polycarbonate/10B detectors on 6 sides of polyethylene (PE) cubes used bare and also embedded at center of PE spheres of 8 different diameters. The system provided well-resolved unfolded directional PN spectra showing thermal and fast PN peaks of 6 sides and mean spectrum in 5 field sizes at isocenter and other locations in 18 MV Siemens ONCOR medical linear accelerator bunker. The neutron spectrometry system developed has unique characteristics such as being simple, efficient, low cost, practical, and insensitive to low-LET radiation with well-resolved directional and mean spectra easily applicable in medicine, health, environment, science and technology in developing and developed laboratories.
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Affiliation(s)
- Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran.
| | - Amir Hakimi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran
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9
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Toth A, Marjanovic M, Gencel I, Petrovic B. Novel design of radiotherapy room suggestion - three-band maze. NUCLEAR TECHNOLOGY AND RADIATION PROTECTION 2021. [DOI: 10.2298/ntrp2104371t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The objective of this study was to analyze the dependence of the neutron dose
from the geometry of the second band of the maze using dosimetric
measurements of neutrons and Monte Carlo simulations, and based on those
results to design a novel radiotherapy room layout. Measurements of the
neutron dose at a two-band maze therapy room were performed for a 15 MeV
photon beam only. Monte Carlo simulations were performed using the GEANT4
toolkit. In order to obtain the geometry dependence, we were changing the
second band angle while we kept the length, height, and width the same as in
reality. Results show that the highest calculated dose was obtained for
the 60? angle of the second maze. It is 17 % higher than for standard 0?
angle. For 30? it was 30 % smaller and for 90? was 10% smaller. Although
the lowest dose was obtained for 30? band angle with calculations, it is not
very practical for clinical use. Clinically the most interesting would be
the 90? angle which is practically a short three-band maze, which could be
promising from the perspective of neutron radiation protection since it
could offer a compact constructional solution, and better optimization of
the available space.
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Affiliation(s)
- Arpad Toth
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia + Vin~a Institute of Nuclear Sciences, National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Milana Marjanovic
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia + Department of Physics, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia
| | - Ivan Gencel
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia
| | - Borislava Petrovic
- Oncology Institute of Vojvodina, Sremska Kamenica, Serbia + Department of Physics, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia
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10
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Kry SF, Alvarez P, Cygler JE, DeWerd LA, Howell RM, Meeks S, O'Daniel J, Reft C, Sawakuchi G, Yukihara EG, Mihailidis D. AAPM TG 191: Clinical use of luminescent dosimeters: TLDs and OSLDs. Med Phys 2019; 47:e19-e51. [DOI: 10.1002/mp.13839] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Stephen F. Kry
- The University of Texas MD Anderson Cancer Center Houston TX USA
| | - Paola Alvarez
- The University of Texas MD Anderson Cancer Center Houston TX USA
| | | | | | | | - Sanford Meeks
- University of Florida Health Cancer Center Orlando FL USA
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11
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Miften M, Mihailidis D, Kry SF, Reft C, Esquivel C, Farr J, Followill D, Hurkmans C, Liu A, Gayou O, Gossman M, Mahesh M, Popple R, Prisciandaro J, Wilkinson J. Management of radiotherapy patients with implanted cardiac pacemakers and defibrillators: A Report of the AAPM TG-203 †. Med Phys 2019; 46:e757-e788. [PMID: 31571229 DOI: 10.1002/mp.13838] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/16/2019] [Accepted: 08/28/2019] [Indexed: 11/11/2022] Open
Abstract
Managing radiotherapy patients with implanted cardiac devices (implantable cardiac pacemakers and implantable cardioverter-defibrillators) has been a great practical and procedural challenge in radiation oncology practice. Since the publication of the AAPM TG-34 in 1994, large bodies of literature and case reports have been published about different kinds of radiation effects on modern technology implantable cardiac devices and patient management before, during, and after radiotherapy. This task group report provides the framework that analyzes the potential failure modes of these devices and lays out the methodology for patient management in a comprehensive and concise way, in every step of the entire radiotherapy process.
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Affiliation(s)
- Moyed Miften
- Task Group 203, Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Dimitris Mihailidis
- Task Group 203, University of Pennsylvania, Perelman Center for Advanced Medicine, Philadelphia, PA, 19104, USA
| | - Stephen F Kry
- Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Chester Reft
- Department of Radiation Oncology, University of Chicago, Chicago, IL, 60637, USA
| | - Carlos Esquivel
- Department of Radiation Oncology, UT Health Sciences Center, San Antonio, TX, 78229, USA
| | - Jonathan Farr
- Division of Radiological Sciences, St. Jude Children's Research Hospital, Memphis, TN, 38105, USA
| | - David Followill
- Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Coen Hurkmans
- Department of Radiotherapy, Catharina Hospital, Eindhoven, the Netherlands
| | - Arthur Liu
- Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, CO, 80045, USA
| | - Olivier Gayou
- Department of Radiation Oncology, Allegheny General Hospital, Pittsburg, PA, 15212, USA
| | - Michael Gossman
- Department of Radiation Oncology, Tri-State Regional Cancer Center, Ashland, KY, 41101, USA
| | - Mahadevappa Mahesh
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA
| | - Richard Popple
- Department of Radiation Oncology, University of Alabama, Birmingham, AL, 35249, USA
| | - Joann Prisciandaro
- Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, 48109, USA
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12
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Novel air-to-tissue conversion factors for fast, epithermal and thermal photoneutrons in a Siemens ONCOR dual energy 18 MV X-ray medical linear accelerator. RADIAT MEAS 2019. [DOI: 10.1016/j.radmeas.2019.106138] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Ali F, Atanackovic J, Boyer C, Festarini A, Kildea J, Paterson LC, Rogge R, Stuart M, Richardson RB. Dosimetric and microdosimetric analyses for blood exposed to reactor-derived thermal neutrons. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2018; 38:1037-1052. [PMID: 29871999 DOI: 10.1088/1361-6498/aaca9f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Thermal neutrons are found in reactor, radiotherapy, aircraft, and space environments. The purpose of this study was to characterise the dosimetry and microdosimetry of thermal neutron exposures, using three simulation codes, as a precursor to quantitative radiobiological studies using blood samples. An irradiation line was designed employing a pyrolytic graphite crystal or-alternatively-a super mirror to expose blood samples to thermal neutrons from the National Research Universal reactor to determine radiobiological parameters. The crystal was used when assessing the relative biological effectiveness for dicentric chromosome aberrations, and other biomarkers, in lymphocytes over a low absorbed dose range of 1.2-14 mGy. Higher exposures using a super mirror will allow the additional quantification of mitochondrial responses. The physical size of the thermal neutron fields and their respective wavelength distribution was determined using the McStas Monte Carlo code. Spinning the blood samples produced a spatially uniform absorbed dose as determined from Monte Carlo N-Particle version 6 simulations. The major part (71%) of the total absorbed dose to blood was determined to be from the 14N(n,p)14C reaction and the remainder from the 1H(n,γ)2H reaction. Previous radiobiological experiments at Canadian Nuclear Laboratories involving thermal neutron irradiation of blood yielded a relative biological effectiveness of 26 ± 7. Using the Particle and Heavy Ion Transport Code System, a similar value of ∼19 for the quality factor of thermal neutrons initiating the 14N(n,p)14C reaction in soft tissue was determined by microdosimetric simulations. This calculated quality factor is of similar high value to the experimentally-derived relative biological effectiveness, and indicates the potential of thermal neutrons to induce deleterious health effects in superficial organs such as cataracts of the eye lens.
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Affiliation(s)
- F Ali
- Radiobiology and Health Branch, Canadian Nuclear Laboratories, Chalk River, ON, K0J 1J0, Canada
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14
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Elazhar H, Deschler T, Létang JM, Nourreddine A, Arbor N. Neutron track length estimator for GATE Monte Carlo dose calculation in radiotherapy. Phys Med Biol 2018; 63:125018. [PMID: 29790859 DOI: 10.1088/1361-6560/aac768] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The out-of-field dose in radiation therapy is a growing concern in regards to the late side-effects and secondary cancer induction. In high-energy x-ray therapy, the secondary neutrons generated through photonuclear reactions in the accelerator are part of this secondary dose. The neutron dose is currently not estimated by the treatment planning system while it appears to be preponderant for distances greater than 50 cm from the isocenter. Monte Carlo simulation has become the gold standard for accurately calculating the neutron dose under specific treatment conditions but the method is also known for having a slow statistical convergence, which makes it difficult to be used on a clinical basis. The neutron track length estimator, a neutron variance reduction technique inspired by the track length estimator method has thus been developped for the first time in the Monte Carlo code GATE to allow a fast computation of the neutron dose in radiotherapy. The details of its implementation, as well as the comparison of its performances against the analog MC method, are presented here. A gain of time from 15 to 400 can be obtained by our method, with a mean difference in the dose calculation of about 1% in comparison with the analog MC method.
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Affiliation(s)
- H Elazhar
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
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15
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Hosseinzadeh E, Banaee N, Nedaie HA. Monte Carlo calculation of photo-neutron dose produced by circular cones at 18 MV photon beams. Rep Pract Oncol Radiother 2018; 23:39-46. [PMID: 29348733 DOI: 10.1016/j.rpor.2017.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 08/14/2017] [Accepted: 12/11/2017] [Indexed: 11/17/2022] Open
Abstract
Aim The aim of this study is to calculate neutron contamination at the presence of circular cones irradiating by 18 MV photons using Monte Carlo code. Background Small photon fields are one of the most useful methods in radiotherapy. One of the techniques for shaping small photon beams is applying circular cones made of lead. Using this method in high energy photon due to neutron contamination is a crucial issue. Materials and methods Initially, Varian linac producing 18 MV photons was simulated and after validating the code, various circular cones were also simulated. Then, the number of neutrons, neutron equivalent dose and absorbed dose per Gy of photon dose were calculated along the central axis. Results Number of neutrons per Gy of photon dose had their maximum value at depth of 2 cm and these values for 5, 10, 15, 20 and 30 mm circular cones were 9.02, 7.76, 7.61, 6.02 and 5.08 (n cm-2 Gy-1), respectively. Neutron equivalent doses per Gy of photon dose had their maximum at the surface of the phantom and these values for mentioned collimators were 1.48, 1.33, 1.31, 1.12 and 1.08 (mSv Gy-1), respectively. Neutron absorbed doses had their maximum at the surface of the phantom and these values for mentioned collimators sizes were 103.74, 99.71, 95.77, 81.46 and 78.20 (μGy/Gy), respectively. Conclusions As the field size gets smaller, number of neutrons, equivalent and absorbed dose per Gy of photon increase. Also, neutron equivalent dose and absorbed dose are maximum at the surface of phantom and then these values will be decreased.
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Affiliation(s)
- Elham Hosseinzadeh
- Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Nooshin Banaee
- Department of Medical Radiation, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
| | - Hassan Ali Nedaie
- Odette Cancer Centre, University of Toronto, Toronto, Canada
- Joint Cancer Research Center, Radiotherapy Oncology & Radiobiology Research Center, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran
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16
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Hakimi A, Sohrabi M, Rabie Mahdavi S. EFFECTS OF FIELD SIZE AND DEPTH ON PHOTONEUTRON DOSE EQUIVALENT DISTRIBUTIONS IN AN 18 MV X-RAY MEDICAL ACCELERATOR. RADIATION PROTECTION DOSIMETRY 2017; 176:354-364. [PMID: 28338868 DOI: 10.1093/rpd/ncx018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 02/06/2017] [Indexed: 06/06/2023]
Abstract
Photoneutron (PN) dosimetry studies in high-energy X-ray medical accelerators are of high clinical and scientific interest in particular to protect patients undergoing radiotherapy. In this context, fast, epithermal and thermal PN dose equivalent distributions in different field sizes and depths in air and in a multilayer polyethylene phantom were studied. Polycarbonate track dosemeters in contact with a 10B convertor (with or without cadmium cover) when electrochemically etched were applied. PN dose equivalents in air and on the surface of the phantom are linear functions of field size. PN depth dose equivalents versus depth in air at the central axis are almost constant. Fast, epithermal and thermal PN dose equivalent responses versus depth in phantom peak respectively at 0.0, ~3.0 and ~3.0 cm while that of the sum PN dose equivalent value (3.32 ± 0.19 mSv·Gy-1) peaks at ~1 cm. These values confirm those of some studies but contract some others.
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Affiliation(s)
- Amir Hakimi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Islamic Republic of Iran
| | - Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Islamic Republic of Iran
| | - Seied Rabie Mahdavi
- Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Islamic Republic of Iran
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17
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Ezzati AO, Studenski MT. Neutron damage induced in cardiovascular implantable electronic devices from a clinical 18 MV photon beam: A Monte Carlo study. Med Phys 2017; 44:5660-5666. [DOI: 10.1002/mp.12581] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 07/27/2017] [Accepted: 09/01/2017] [Indexed: 11/06/2022] Open
Affiliation(s)
- Ahad Ollah Ezzati
- Department of Physics; University of Tabriz; 29 Bahman Blvd. Tabriz 5166616471 Iran
| | - Matthew T. Studenski
- Department of Radiation Oncology; University of Miami; 1475 NW 12 Ave. Suite 1500 Miami FL 33136 USA
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Measurement of neutron dose in the compensator IMRT treatment. Appl Radiat Isot 2017; 128:136-141. [DOI: 10.1016/j.apradiso.2017.06.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 11/21/2022]
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Kry SF, Bednarz B, Howell RM, Dauer L, Followill D, Klein E, Paganetti H, Wang B, Wuu CS, George Xu X. AAPM TG 158: Measurement and calculation of doses outside the treated volume from external-beam radiation therapy. Med Phys 2017; 44:e391-e429. [DOI: 10.1002/mp.12462] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 05/17/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022] Open
Affiliation(s)
- Stephen F. Kry
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Bryan Bednarz
- Department of Medical Physics; University of Wisconsin; Madison WI 53705 USA
| | - Rebecca M. Howell
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Larry Dauer
- Departments of Medical Physics/Radiology; Memorial Sloan-Kettering Cancer Center; New York NY 10065 USA
| | - David Followill
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Eric Klein
- Department of Radiation Oncology; Washington University; Saint Louis MO 63110 USA
| | - Harald Paganetti
- Department of Radiation Oncology; Massachusetts General Hospital and Harvard Medical School; Boston MA 02114 USA
| | - Brian Wang
- Department of Radiation Oncology; University of Louisville; Louisville KY 40202 USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology; Columbia University; New York NY 10032 USA
| | - X. George Xu
- Department of Mechanical, Aerospace, and Nuclear Engineering; Rensselaer Polytechnic Institute; Troy NY 12180 USA
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Fast, epithermal and thermal photoneutron dosimetry in air and in tissue equivalent phantom for a high-energy X-ray medical accelerator. Z Med Phys 2017; 28:49-62. [PMID: 28546005 DOI: 10.1016/j.zemedi.2017.04.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 04/16/2017] [Accepted: 04/17/2017] [Indexed: 12/14/2022]
Abstract
Photoneutron (PN) dosimetry in fast, epithermal and thermal energy ranges originated from the beam and albedo neutrons in high-energy X-ray medical accelerators is highly important from scientific, technical, radiation protection and medical physics points of view. Detailed dose equivalents in the fast, epithermal and thermal PN energy ranges in air up to 2m as well as at 35 positions from the central axis of 12 cross sections of the phantom at different depths were determined in 18MV X-ray beams of a Siemens ONCOR accelerator. A novel dosimetry method based on polycarbonate track dosimeters (PCTD)/10B (with/without cadmium cover) was used to determine and separate different PN dose equivalents in air and in a multilayer polyethylene phantom. Dose equivalent distributions of PNs, as originated from the main beam and/or albedo PNs, on cross-plane, in-plane and diagonal axes in 10cm×10cm fields are reported. PN dose equivalent distributions on the 3 axes have their maxima at the isocenter. Epithermal and thermal PN depth dose equivalent distributions in the phantom for different positions studied peak at ∼3cm depth. The neutron dosimeters used for the first time in such studies are highly effective for separating dose equivalents of PNs in the studied energy ranges (beam and/or albedo). The PN dose equivalent data matrix made available in this paper is highly essential for detailed patient dosimetry in general and for estimating secondary cancer risks in particular.
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Out-of-field in vivo dosimetry using TLD in SABR for primary kidney cancer involving mixed photon fields. Phys Med 2017; 37:9-15. [PMID: 28535921 DOI: 10.1016/j.ejmp.2017.03.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Revised: 03/21/2017] [Accepted: 03/27/2017] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To assess out-of-field dose using three different variants of LiF thermoluminescence dosimeters (TLD) for ten patients who underwent stereotactic ablative body radiotherapy (SABR) for primary renal cell carcinoma (RCC) and compare with treatment planning system (TPS) dose calculations. METHODS AND MATERIALS Thermoluminescent dosimeter (TLD) measurements were conducted at 20, 30, 40 and 50cm from isocentre on ten patients undergoing SABR for primary RCC. Three types of high-sensitivity LiF:Mg,Cu,P TLD material with different 6Li/7Li isotope ratios were used. Patient plans were calculated using Eclipse Anisotropic Analytical Algorithm (AAA) for clinical evaluation and recalculated using Pencil Beam Convolution (PBC) algorithm for comparison. RESULTS Both AAA and PBC showed diminished accuracy for photon doses at increasing distance out-of-field. At 50cm, measured photon dose was 0.3cGy normalised to a 10Gy prescription on average with only small variation across all patients. This is likely due to the leakage component of the out-of-field dose. The 6Li-enriched TLD materials showed increased signal attributable to additional neutron contribution. CONCLUSION LiF:Mg,Cu,P TLD containing 6Li is sensitive enough to measure out-of-field dose 50cm from isocentre however will over-estimate the photon component of out-of-field dose in high energy treatments due to the presence of thermal neutrons. 7Li enriched materials which are insensitive to neutrons are therefore required for accurate photon dosimetry. Neutron signal has been shown here to increase with MUs and is higher for patients treated using certain non coplanar beam arrangements. Further work is required to convert this additional neutron signal to dose.
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Ezzati A, Studenski M. Neutron dose in and out of 18 MV photon fields. Appl Radiat Isot 2017; 122:186-192. [DOI: 10.1016/j.apradiso.2017.01.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/21/2017] [Accepted: 01/27/2017] [Indexed: 10/20/2022]
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Hakimi A, Sohrabi M. Photoneutron depth dose equivalent distributions in high-energy X-ray medical accelerators by a novel position-sensitive dosimeter. Phys Med 2017; 36:73-80. [PMID: 28410689 DOI: 10.1016/j.ejmp.2017.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 03/17/2017] [Accepted: 03/18/2017] [Indexed: 10/19/2022] Open
Abstract
PURPOSE The purpose of this study was to; (1) investigate employing a novel position-sensitive mega-size polycarbonate (MSPC) dosimeter for photoneutron (PN) depth, profile and dose equivalent distributions studies in a multilayer polyethylene phantom in a Siemens ONCOR accelerator, and (2) develop depth dose equivalent distribution matrix data at different depths and positions of the phantom for patient PN dose equivalent determination and in particular for PN secondary cancer risk estimation. METHODS Position-sensitive MSPC dosimeters were successfully exposed at 9 different depths of the phantom in a 10×10cm2 X-ray field. The dosimeters were processed in mega-size electrochemical chambers at optimum conditions. Each MSPC dosimeter was placed at a known phantom depth for PN depth dose equivalents and profiles on transverse, longitudinal and diagonal axes and isodose equivalent distribution studies in and out of the X-ray beam. RESULTS PN dose equivalent distributions at any depth showed the highest value at the beam central axis and decreases as the distance increases. PN dose equivalent at any position studied in the axes has a maximum value on the phantom surface which decreases as depth increases due to flux reduction by multi-elastic scattering interactions. CONCLUSIONS Extensive PN dose equivalent matrix data at different depths and positions in the phantom were determined. The position-sensitive MSPC dosimeters proved to be highly efficient for PN depth, profile and isodose equivalent distribution studies. The extensive data obtained highly assists for determining PN dose equivalent of a patient undergoing high-energy X-ray therapy and for PN secondary cancer risk estimation.
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Affiliation(s)
- Amir Hakimi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran
| | - Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran.
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Keehan S, Smith RL, Millar J, Esser M, Taylor ML, Lonski P, Kron T, Franich RD. Activation of hip prostheses in high energy radiotherapy and resultant dose to nearby tissue. J Appl Clin Med Phys 2017; 18:100-105. [PMID: 28300363 PMCID: PMC5689951 DOI: 10.1002/acm2.12058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 11/05/2016] [Accepted: 01/05/2017] [Indexed: 11/26/2022] Open
Abstract
High energy radiotherapy can produce contaminant neutrons through the photonuclear effect. Patients receiving external beam radiation therapy to the pelvis may have high‐density hip prostheses. Metallic materials such as those in hip prostheses, often have high cross‐sections for neutron interaction. In this study, Thackray (UK) prosthetic hips have been irradiated by 18 MV radiotherapy beams to evaluate the additional dose to patients from the activation products. Hips were irradiated in‐ and out‐of field at various distances from the beam isocenter to assess activation caused in‐field by photo‐activation, and neutron activation which occurs both in and out‐of‐field. NaI(Tl) scintillator detectors were used to measure the subsequent gamma‐ray emissions and their half‐lives. High sensitivity Mg, Cu, P doped LiF thermoluminescence dosimeter chips (TLD‐100H) were used to measure the subsequent dose at the surface of a prosthesis over the 12 h following an in‐field irradiation of 10,000 MU to a hip prosthesis located at the beam isocenter in a water phantom. 53Fe, 56Mn, and 52V were identified within the hip following irradiation by radiotherapy beams. The dose measured at the surface of a prosthesis following irradiation in a water phantom was 0.20 mGy over 12 h. The dose at the surface of prostheses irradiated to 200 MU was below the limit of detection (0.05 mGy) of the TLD100H. Prosthetic hips are activated by incident photons and neutrons in high energy radiotherapy, however, the dose resulting from activation is very small.
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Affiliation(s)
- Stephanie Keehan
- School of Science, RMIT University, Melbourne, Victoria, Australia
| | - Ryan L Smith
- School of Science, RMIT University, Melbourne, Victoria, Australia.,William Buckland Radiotherapy Centre, The Alfred Hosptial, Melbourne, Victoria, Australia
| | - Jeremy Millar
- School of Science, RMIT University, Melbourne, Victoria, Australia.,William Buckland Radiotherapy Centre, The Alfred Hosptial, Melbourne, Victoria, Australia
| | - Max Esser
- Department of Orthopaedic Surgery, The Alfred Hosptial, Melbourne, Victoria, Australia
| | - Michael L Taylor
- School of Science, RMIT University, Melbourne, Victoria, Australia
| | - Peta Lonski
- School of Science, RMIT University, Melbourne, Victoria, Australia.,Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Tomas Kron
- School of Science, RMIT University, Melbourne, Victoria, Australia.,Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Rick D Franich
- School of Science, RMIT University, Melbourne, Victoria, Australia
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Arbor N, Higueret S, Elazhar H, Combe R, Meyer P, Dehaynin N, Taupin F, Husson D. Real-time detection of fast and thermal neutrons in radiotherapy with CMOS sensors. Phys Med Biol 2017; 62:1920-1934. [PMID: 28192285 DOI: 10.1088/1361-6560/aa5bc9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The peripheral dose distribution is a growing concern for the improvement of new external radiation modalities. Secondary particles, especially photo-neutrons produced by the accelerator, irradiate the patient more than tens of centimeters away from the tumor volume. However the out-of-field dose is still not estimated accurately by the treatment planning softwares. This study demonstrates the possibility of using a specially designed CMOS sensor for fast and thermal neutron monitoring in radiotherapy. The 14 microns-thick sensitive layer and the integrated electronic chain of the CMOS are particularly suitable for real-time measurements in γ/n mixed fields. An experimental field size dependency of the fast neutron production rate, supported by Monte Carlo simulations and CR-39 data, has been observed. This dependency points out the potential benefits of a real-time monitoring of fast and thermal neutron during beam intensity modulated radiation therapies.
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Affiliation(s)
- Nicolas Arbor
- Université de Strasbourg, IPHC, 23 rue du Loess 67037 Strasbourg, France. CNRS, UMR7178, 67037 Strasbourg, France
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Romero-Expósito M, Domingo C, Sánchez-Doblado F, Ortega-Gelabert O, Gallego S. Experimental evaluation of neutron dose in radiotherapy patients: Which dose? Med Phys 2016; 43:360. [PMID: 26745929 DOI: 10.1118/1.4938578] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The evaluation of peripheral dose has become a relevant issue recently, in particular, the contribution of secondary neutrons. However, after the revision of the Recommendations of the International Commission on Radiological Protection, there has been a lack of experimental procedure for its evaluation. Specifically, the problem comes from the replacement of organ dose equivalent by the organ-equivalent dose, being the latter "immeasurable" by definition. Therefore, dose equivalent has to be still used although it needs the calculation of the radiation quality factor Q, which depends on the unrestricted linear energy transfer, for the specific neutron irradiation conditions. On the other hand, equivalent dose is computed through the radiation weighting factor wR, which can be easily calculated using the continuous function provided by the recommendations. The aim of the paper is to compare the dose equivalent evaluated following the definition, that is, using Q, with the values obtained by replacing the quality factor with wR. METHODS Dose equivalents were estimated in selected points inside a phantom. Two types of medical environments were chosen for the irradiations: a photon- and a proton-therapy facility. For the estimation of dose equivalent, a poly-allyl-diglicol-carbonate-based neutron dosimeter was used for neutron fluence measurements and, additionally, Monte Carlo simulations were performed to obtain the energy spectrum of the fluence in each point. RESULTS The main contribution to dose equivalent comes from neutrons with energy higher than 0.1 MeV, even when they represent the smallest contribution in fluence. For this range of energy, the radiation quality factor and the radiation weighting factor are approximately equal. Then, dose equivalents evaluated using both factors are compatible, with differences below 12%. CONCLUSIONS Quality factor can be replaced by the radiation weighting factor in the evaluation of dose equivalent in radiotherapy environments simplifying the practical procedure.
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Affiliation(s)
- M Romero-Expósito
- Grup de Recerca en Radiacions Ionizants (GRRI), Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - C Domingo
- Grup de Recerca en Radiacions Ionizants (GRRI), Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - F Sánchez-Doblado
- Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla 41009, SpainServicio de Radiofísica, Hospital Universitario Virgen Macarena, Sevilla 41009, Spain
| | - O Ortega-Gelabert
- Grup de Recerca en Radiacions Ionizants (GRRI), Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | - S Gallego
- Grup de Recerca en Radiacions Ionizants (GRRI), Departament de Física, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
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Horst F, Czarnecki D, Zink K. The influence of neutron contamination on dosimetry in external photon beam radiotherapy. Med Phys 2016; 42:6529-36. [PMID: 26520743 DOI: 10.1118/1.4933246] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
PURPOSE Photon fields with energies above ∼7 MeV are contaminated by neutrons due to photonuclear reactions. Their influence on dosimetry-although considered to be very low-is widely unexplored. METHODS In this work, Monte Carlo based investigations into this issue performed with fluka and egsnrc are presented. A typical Linac head in 18 MV-X mode was modeled equivalently within both codes. egsnrc was used for the photon and fluka for the neutron production and transport simulation. Water depth dose profiles and the response of different detectors (Farmer chamber, TLD-100, TLD-600H, and TLD-700H chip) in five representative depths were simulated and the neutrons' impact (neutron absorbed dose relative to photon absorbed dose) was calculated. To take account of the neutrons' influence, a theoretically required correction factor was defined and calculated for five representative water depths. RESULTS The neutrons' impact on the absorbed dose to water was found to be below 0.1% for all depths and their impact on the response of the Farmer chamber and the TLD-700H chip was found to be even less. For the TLD-100 and the TLD-600H chip it was found to be up to 0.3% and 0.7%, respectively. The theoretical correction factors to be applied to absorbed dose to water values measured with these four detectors in a depth different from the reference/calibration depth were calculated and found to be below 0.05% for the Farmer chamber and the TLD-700H chip, but up to 0.15% and 0.35% for the TLD-100 and TLD-600H chips, respectively. In thermoluminescence dosimetry the neutrons' influence (and therefore the additional inaccuracy in measurement) was found to be higher for TLD materials whose 6Li fraction is high, such as TLD-100 and TLD-600H, resulting from the thermal neutron capture reaction on 6Li. CONCLUSIONS The impact of photoneutrons on the absorbed dose to water and on the response of a typical ionization chamber as well as three different types of TLD chips was quantified and was as expected found to be very low relative to that of the primary photons. For most practical reasons the neutrons' influence on dosimetry might be neglected while for absolute precise thermoluminescence dosimetry in high energy photon fields, the use of TLD-700H (<0.03% 6Li) instead of the commonly used TLD-100 (7.4% 6Li) or even the extra neutron sensitive TLD-600H is recommended (95.6% 6Li) due to the additional inaccuracy in measurement for TLD materials with a high 6Li fraction.
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Affiliation(s)
- Felix Horst
- Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences Giessen, Giessen D-35390, Germany
| | - Damian Czarnecki
- Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences Giessen, Giessen D-35390, Germany
| | - Klemens Zink
- Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences Giessen, Giessen D-35390, Germany and Department of Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg D-35043, Germany
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Sohrabi M, Hakimi A, Mahdavi SR. A novel position-sensitive mega-size dosimeter for photoneutrons in high-energy X-ray medical accelerators. Phys Med 2016; 32:778-86. [PMID: 27174443 DOI: 10.1016/j.ejmp.2016.05.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 05/03/2016] [Accepted: 05/05/2016] [Indexed: 11/15/2022] Open
Abstract
PURPOSE A novel position-sensitive mega-size polycarbonate (MSPC) dosimeter is introduced. It provides photoneutron (PN) dose equivalent matrix of positions in and out of a beam of a high energy X-ray medical accelerator under a single exposure. METHODS A novel position-sensitive MSPC dosimeter was developed and applied. It has an effective etched area of 50×50cm(2), as used in this study, processed in a mega-size electrochemical etching chamber to amplify PN-induced-recoil tracks to a point viewed by the unaided eyes. Using such dosimeters, PN dose equivalents, dose equivalent profiles and isodose equivalent distribution of positions in and out of beams for different X-ray doses and field sizes were determined in a Siemens ONCOR Linac. RESULTS The PN dose equivalent at each position versus X-ray dose was linear up to 20Gy studied. As the field size increased, the PN dose equivalent in the beam was also increased but it remained constant at positions out of the beam up to 20cm away from the beam edge. The jaws and MLCs due to material differences and locations relative to the target produce different PN contributions. CONCLUSIONS The MSPC dosimeter introduced in this study is a perfect candidate for PN dosimetry with unique characteristics such as simplicity, efficiency, dose equivalent response, large size, flexibility to be bent, resembling the patient's skin, highly position-sensitive with high spatial resolution, highly insensitive to X-rays, continuity in measurements and need to a single dosimeter to obtain PN dose equivalent matrix data under a single X-ray exposure.
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Affiliation(s)
- Mehdi Sohrabi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran.
| | - Amir Hakimi
- Health Physics and Dosimetry Research Laboratory, Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, Iran
| | - Seyed Rabi Mahdavi
- Department of Medical Physics, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
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Najem M, Abolaban F, Podolyák Z, Spyrou N. Neutron production from flattening filter free high energy medical linac: A Monte Carlo study. Radiat Phys Chem Oxf Engl 1993 2015. [DOI: 10.1016/j.radphyschem.2015.01.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Mohammadi N, Miri-Hakimabad H, Rafat-Motavalli L, Akbari F, Abdollahi S. Patient-specific voxel phantom dosimetry during the prostate treatment with high-energy linac. J Radioanal Nucl Chem 2014. [DOI: 10.1007/s10967-014-3872-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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31
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Wakabayashi G, Nohtomi A, Yahiro E, Fujibuchi T, Fukunaga J, Umezu Y, Nakamura Y, Nakamura K, Hosono M, Itoh T. Applicability of self-activation of an NaI scintillator for measurement of photo-neutrons around a high-energy X-ray radiotherapy machine. Radiol Phys Technol 2014; 8:125-34. [DOI: 10.1007/s12194-014-0300-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 10/25/2014] [Accepted: 10/26/2014] [Indexed: 11/29/2022]
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Gressier V. Review of neutron calibration facilities and monitoring techniques: new needs for emerging fields. RADIATION PROTECTION DOSIMETRY 2014; 161:27-36. [PMID: 24344349 DOI: 10.1093/rpd/nct328] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Neutron calibration facilities and monitoring techniques have been developed since the middle of the 20th century to support research and nuclear power energy development. The technical areas needing reference neutron fields and related instruments were mainly cross section measurements, radiation protection, dosimetry and fission reactors, with energy ranging from a few millielectronvolts to about 20 MeV. The reference neutron fields and calibration techniques developed for these purposes will be presented in this paper. However, in recent years, emerging fields have brought new needs for calibration facilities and monitoring techniques. These new challenges for neutron metrology will be exposed with their technical difficulties.
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Affiliation(s)
- V Gressier
- Institute for Radiological Protection and Nuclear Safety, Saint-Paul lez Durance 13115, France
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33
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Najem M, Spyrou N, Podolyák Z, Abolaban F. The physical characteristics of the 15MV Varian Clinac 2100C unflattened beam. Radiat Phys Chem Oxf Engl 1993 2014. [DOI: 10.1016/j.radphyschem.2013.04.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Harrison R. Introduction to dosimetry and risk estimation of second cancer induction following radiotherapy. RADIAT MEAS 2013. [DOI: 10.1016/j.radmeas.2013.01.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Krmar M, Nikolić D, Kuzmanović A, Kuzmanović Z, Ganezer K. The effect of a paraffin screen on the neutron dose at the maze door of a 15 MV linear accelerator. Med Phys 2013; 40:083902. [PMID: 23927362 DOI: 10.1118/1.4812433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE The purpose of this study was to explore the effects of a paraffin screen located at various positions in the maze on the neutron dose equivalent at the maze door. METHODS The neutron dose equivalent was measured at the maze door of a room containing a 15 MV linear accelerator for x-ray therapy. Measurements were performed for several positions of the paraffin screen covering only 27.5% of the cross-sectional area of the maze. The neutron dose equivalent was also measured at all screen positions. Two simple models of the neutron source were considered in which the first assumed that the source was the cross-sectional area at the inner entrance of the maze, radiating neutrons in an isotropic manner. In the second model the reduction in the neutron dose equivalent at the maze door due to the paraffin screen was considered to be a function of the mean values of the neutron fluence and energy at the screen. RESULTS The results of this study indicate that the equivalent dose at the maze door was reduced by a factor of 3 through the use of a paraffin screen that was placed inside the maze. It was also determined that the contributions to the dosage from areas that were not covered by the paraffin screen as viewed from the dosimeter, were 2.5 times higher than the contributions from the covered areas. This study also concluded that the contributions of the maze walls, ceiling, and floor to the total neutron dose equivalent were an order of magnitude lower than those from the surface at the far end of the maze. CONCLUSIONS This study demonstrated that a paraffin screen could be used to reduce the neutron dose equivalent at the maze door by a factor of 3. This paper also found that the reduction of the neutron dose equivalent was a linear function of the area covered by the maze screen and that the decrease in the dose at the maze door could be modeled as an exponential function of the product φ·E at the screen.
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Affiliation(s)
- M Krmar
- Physics Department, Faculty of Science, University of Novi Sad, Novi Sad 21000, Serbia.
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Expósito MR, Sánchez-Nieto B, Terrón JA, Domingo C, Gómez F, Sánchez-Doblado F. Neutron contamination in radiotherapy: Estimation of second cancers based on measurements in 1377 patients. Radiother Oncol 2013; 107:234-41. [DOI: 10.1016/j.radonc.2013.03.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2012] [Revised: 02/27/2013] [Accepted: 03/09/2013] [Indexed: 11/28/2022]
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Vega-Carrillo H, Martínez-Ovalle S, Lallena A, Mercado G, Benites-Rengifo J. Neutron and photon spectra in LINACs. Appl Radiat Isot 2012; 71 Suppl:75-80. [DOI: 10.1016/j.apradiso.2012.03.034] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 03/06/2012] [Accepted: 03/20/2012] [Indexed: 10/28/2022]
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Martinez-Ovalle SA, Barquero R, Gomez-Ros JM, Lallena AM. Neutron dosimetry in organs of an adult human phantom using linacs with multileaf collimator in radiotherapy treatments. Med Phys 2012; 39:2854-66. [PMID: 22559658 DOI: 10.1118/1.4704527] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To calculate absorbed doses due to neutrons in 87 organs/tissues for anthropomorphic phantoms, irradiated in position supine (head first into the gantry) with orientations anteroposterior (AP) and right-left (RLAT) with a 18 MV accelerator. Conversion factors from monitor units to μGy per neutron in organs, equivalent doses in organs/tissues, and effective doses, which permit to quantify stochastic risks, are estimated. METHODS MAX06 and FAX06 phantoms were modeled with MCNPX and irradiated with a 18 MV Varian Clinac 2100C/D accelerator whose geometry included a multileaf collimator. Two actual fields of a pelvic treatment were simulated using electron-photon-neutron coupled transport. Absorbed doses due to neutrons were estimated from kerma. Equivalent doses were estimated using the radiation weighting factor corresponding to an average incident neutron energy 0.47 MeV. Statistical uncertainties associated to absorbed doses, as calculated by MCNPX, were also obtained. RESULTS Largest doses were absorbed in shallowest (with respect to the neutron pathway) organs. In μGyMU(-1), values of 2.66 (for penis) and 2.33 (for testes) were found in MAX06, and 1.68 (for breasts), 1.05 (for lenses of eyes), and 0.94 (for sublingual salivary glands) in FAX06, in AP orientation. In RLAT, the largest doses were found for bone tissues (leg) just at the entrance of the beam in the body (right side in our case). Values, in μGyMU(-1), of 1.09 in upper leg bone right spongiosa, for MAX06, and 0.63 in mandible spongiosa, for FAX06, were found. Except for gonads, liver, and stomach wall, equivalent doses found for FAX06 were, in both orientations, higher than for MAX06. Equivalent doses in AP are higher than in RLAT for all organs/tissues other than brain and liver. Effective doses of 12.6 and 4.1 μSvMU(-1) were found for AP and RLAT, respectively. The organs/tissues with larger relative contributions to the effective dose were testes and breasts, in AP, and breasts and red marrow, in RLAT. Equivalent and effective doses obtained for MAX06/FAX06 were smaller (between 2 and 20 times) than those quoted for the mathematical phantoms ADAM/EVA in ICRP-74. CONCLUSIONS The new calculations of conversion coefficients for neutron irradiation in AP and RLAT irradiation geometries show a reduction in the values of effective dose by factors 7 (AP) and 6 (RLAT) with respect to the old data obtained with mathematical phantoms. The existence of tissues or anatomical regions with maximum absorbed doses, such as penis, lens of eyes, fascia (part of connective tissue), etc., organs/tissues that classic mathematical phantoms did not include because they were not considered for the study of stochastic effects, has been revealed. Absorbed doses due to photons, obtained following the same simulation methodology, are larger than those due to neutrons, reaching values 100 times larger as the primary beam is approached. However, for organs far from the treated volume, absorbed photon doses can be up to three times smaller than neutron ones. Calculations using voxel phantoms permitted to know the organ dose conversion coefficients per MU due to secondary neutrons in the complete anatomy of a patient.
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Affiliation(s)
- S A Martinez-Ovalle
- Grupo de Física Nuclear Aplicada y Simulación, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
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Martínez-Ovalle SA, Barquero R, Gómez-Ros JM, Lallena AM. Neutron dose equivalent and neutron spectra in tissue for clinical linacs operating at 15, 18 and 20 MV. RADIATION PROTECTION DOSIMETRY 2011; 147:498-511. [PMID: 21233098 DOI: 10.1093/rpd/ncq501] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this work, the dose equivalent due to photoneutrons and the neutron spectra in tissue was calculated for various linacs (Varian Clinac 2100C, Elekta Inor, Elekta SL25 and Siemens Mevatron KDS) operating at energies between 15 and 20 MV, using the Monte Carlo code MCNPX (v. 2.5). The dose equivalent in an ICRU tissue phantom has been calculated for anteroposterior treatments with a detailed simulation of the geometry of the linac head and the coupled electron-photon-neutron transport. Neutron spectra at the phantom entrance and at 1-cm depth in the phantom, depth distribution of the neutron fluence in the beam axis and dose distributions outside the beam axis at various depths have also been calculated and compared with previously published results. The differences between the neutron production of the various linacs considered has been analysed. Varian linacs show a larger neutron production than the Elekta and Siemens linacs at the same operating energy. The dose equivalent due to neutrons produced by medical linacs operating at energies >15 MeV is relevant and should not be neglected because of the additional doses that patients can receive.
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Affiliation(s)
- S A Martínez-Ovalle
- Departamento de Física, Universidad Pedagógica y Tecnológica de Colombia, Tunja, Colombia
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